Gaseous discharge lamp and starting mechanism therefor



April 25, 1944. s E 2,347,222

GASEOUS DISCHARGE LAMP AND STARTING MECHANISM THEREFOR 7 Filed Jan. 23,1941 Tic:,.2..

VOLTS 3 5. j B m m.

,5 i M /3/ M -11- INVENTOR Pm/P SIrZEA BY M/T M am w W r41) ATTORN EYSand starting mechanism therefor.

Patented Apr. 25, 1944 GASEOUS DISCHARGE LAMP AND STAETENG MECHANISMTHEREFOR Philip Sitzer, Irvington, Sol Lamp Works Inc.,

tion of Delaware N. J., assignor to Tang Newark, N. .l., a cor oratApplication January 23, 1941, Serial No. 375,556

20 Claims.

.to thermally operated circuits utilizing such This invention relatesswitches and control switches.

One object 01' the invention is a fluorescent lamp embodying a novel andimproved starting circuit.

A further object of the invention is a novel and improved combinedfluorescent or gaseous lamp and starting mechanism.

A further object of the invention is a novel and improved startingcircuit for fluorescent and other gaseous discharge lamps.

A further object of the invention is a novel and improved thermallyoperated control switch.

A further object of the invention is a novel and improved thermallyoperated switch and circults controlled thereby.

Other objects of the invention will hereinafter appear.

For a better understanding of the invention reference may be had to theaccompanying drawing forming a part oi this application wherein- Fig. 1illustrates a fluorescent lamp and starting mechanism embodying theinvention;

Fig. 2 is a diagram illustrating the voltage current characteristic ofan element of the starting mechanism; and

Figs. 3 to 11 inclusive illustrate the utilization of athermally'operated switch embodying the invention in other controlcircuits.

Referring to Figs. 1 and 2 of the drawing, the invention is illustratedas embodied in a fluorescent or gaseous discharge illumination device Aconventional fluorescent or gaseous discharge envelope is indicated atI, having the conventional heating electrode filaments 2 in the oppositeends thereof. The numeral 3 indicates an alternating current supply linefor the lamp tube l and the conventional inductive reactance (isillustrated as connected in series with the lamp 2 in order to limit therunning current to a definite value.

In order to initiate the discharge between the electrodes 2 or to startthe lamp a higher starting voltage is required than is required forrunning the lamp 'or-keeping it lighted after the arc discharge is oncestarted. The heating filaments 2 are utilized to ionize the gas or gasesin the tube I to facilitate the starting operation. This inventionincludes a resistance heater element M and a thermally operated elementB, with the resistance element M connected across the line conductors 3in series with the filaments 2 and with the thermally operated element13 controlling the relatively movable contacts and 6 to temporarilyshort-circuit the resistance element M. The circuit of the resistanceelement M includes the conductors l and leading Irespectively to one endof the heating filaments 2, with the other ends or" the filamentsconnected with the line conductors A condenser 9 is connected across thecontacts 5 and ii in order to minimize sparking and assist in thestarting.

The resistance element M is composed of a material whose voltage-currentcharacteristic curve is characterized by a rapid and out of proportionincrease in current with. increase in voltage. This is shown graphicallyby the voltage vs. current curve in Figure 2 wherein it is observed thatthe slope of the curve is changed at each succes sive point whichindicates that the change in cur rent is out of proportion to the changein volt age. This general characteristic is to he ex hibited by any ofthe materials lvi used this invention. It is also understood that thecurve 0 Figure 2 is representative or a particular quality and varied oraltered in uuant y and degree depend ing upon the type of ma iai used,the sine and shape, and the temperature which material M is allowed toattain as the ruin actors aifecting the curve. As stated above. however,the general characteristic of material he is to he such that the currentflowing through the material M, due to an applied increasing voltage,increase at a rate greater than and out of proportion to the increase involtage. Also, the greater the rate of current change with a certain.change in volt age, the more suited is the material M to the invention.The characteristic detailed above is uti lized in the fluorescent lampor fluorescent lamp circuit of Figure l in the starting of the lamp, themarked rising characteristic of th currentvoltage curve being utilizedto furnish the heat required to operate the thermally responsive elementB when the line circuit is first closed. Thus, upon closure of the linecircuit (the power line and switch being omitted for convenience inillustration) the full line voltage is applied to the inductivereactance the filaments and the resistance element M, and in some cases,this voltage is boosted for some types of fluorescent lamps by a step-uptransformer control which is omitted for convenience in illustration;with the circuit thus closed and by proportion of voltages in a circuitof this kind (resistance of material M being comparatively very high)pracmaterial or" one melons and may tically the full line voltage isapplied across re sistance M, as for one example, 165 volts, the currentflow through the resistance element M becomes, comparatively, very largeas indicated by the characteristic curve in Figure 2 with the resultthat the heat units dissipated by the resistance element are sufficientto operate the thermally responsive element B which is caused to bend inthe direction indicated by the arrow to close the contacts and 6 and toshort-circuit the resistance element M. Under this condition, thecurrent flow in the circuit becomes very large, limited mainly by thereactance 6 and causing the filaments 2 to be heated. Simultaneously,the short-circuiting of the resistance M results in rapid cooling of thesame due to the shunting of the current with the result that thethermally responsive element B after a suitable time delay, opens. Thetime delay in the opening of the element B is sufdciently long to allowproper heating of the filaments 2, and the starting or the dischargethrough the lamp tube i results from the high inductive surge voltageinduced by the reactance it when the short-circuit current flow isinterrupted by the opening of contacts 5 and 15. The startin is alsoaided by the heated condition of the filaments 2 which partially ionizesthe gases in the lamp tube i.

If perchance the arc does not. strike at the first cycle of operation ofthe element B, a second cycle of operation of the element B will resultin closure and after suitable time delay, opening of contacts 5 and 6with the attendant heating of the filaments 2 during the closed periodand inducing of a high voltage surge at the instant of opening, andrepeated operations of the element B, until the lamp starts, will assurethe starting of the lamp, although ordinarily only one closing andopening operation of the contacts ti and 6 is necessary to efitect thisresult. After the arc is struck and the lamp is operating, the currentflow through the resistance M is so small as to render negligible thepower which is constantly consumed thereby during the operation of thelamp, the voltage drop across the operating lamp (and, thereby, thevoltage across resistor element M) being for the example of aconventional lamp taken above, about 120 volts. Thus for a material Mwhose current voltage characteristic would be illustrated by Figure 2 itcan be seen that the current flow through the resistance material Mwhile greater than 1% ma. at 165 volts is only 4 ma. at 120 volts, thismaking it relatively easy to prevent closure of contacts'5 and 6 at 120volts when the lamp is operating and thereby assure of a properlyfunctioning starting mechanism.

The resistance heater element M may be composed of any suitable materialgiving the desired current voltage characteristic, but preferably it isa carborundum or carborundum-like material or a material composed mainlyof silicon carbide or silicon carbide and carbon combined with anothermaterial, as for example a material containing 75% of silicon carbonwith around 25% iron pyrite or 25% galena or 25% zinc oxide. A materialof the character described in Patent No. 1,822,742 may be used andparticularly good results have been obtained with the use of a materialknown in the trade as Thyrite which comprises essentially siliconcarbide, a conducting material such as carbon and a binder. It isunderstood, however, that although this is the at present preferredmaterial, other materials having similar characteristics may be employedin the making of the resistance heater ele- -ment M.

The thermally responsive element 18 may be of any suitable thermally orheat responsive material as for example a bi-metallic strip which bendsupon being subjected to heat.

The thermally controlled switch comprising the resistance heater elementM and the thermally responsive element B-has other uses than thatillustrated in Fig. 1, as for example shown in Figs. 3 to 11. I

Fig. 3 shows the utilization of this switch as a relay to control acircuit H by applying a controlling voltage at E2, the arrow indicatingthe direction of bending of the element B upon being heated by theresistance element M of the characteristics shown in Fig. 2. Fig. ashows a control similar to Fig. 3 with the control circuit normally openbut in this case the element 13 assumes a substantially straightposition in the cold'condition, and bends in a direction away iron: theheater or resistance material M.

" Figs. 5 and 6 are views of control circuits sim- Figs. 7 and 8 arecircuits similar to the controls of Figs. 3 to 6, but here there are twocontrolled circuits the element 18 controlling two fixed contacts andone of the circuits being nor mally closed and the other one normallyopen, and by the word normally" meaning the cold condition.

Figs. 9 and 10 show the utilization of the thermally operated switch B,M in a circuit to be intermittently closed or flashed, the circuit to bethus controlled and operated being connected with the terminals l3.

Fig. 11 indicates the use of the switch B,M in a signal circuit toindicate an abnormal voltage applied to the terminals it, an indicatinglamp it being connected in series with the switch which by itsintermittent lighting by the intermittent closing of the switch Bindicates the abnormal voltage.

Although the invention is illustrated in Fig. 1 as applied to analternating current system and lamp, it is understood that the principleis applicable to direct current supply circuits and lamps, Although thegeneral arrangement of the invention as described above is desired atresent, it is to be understood that other modifications thereof may bemade without. departing from the spirit and the scope of the appendedclaims.

I claim:

l. The combination of a gaseous discharge device with a starting andoperating circuit therefor comprising an envelope with heatingelectrodes therein, a resistance heating element connected in serieswith said electrodes and having a voltage-current characteristiccharacterized by the rapid and out-of-proportion increase in amperagewith increase in voltage above the range of the operating voltage of thedevice, and a thermally responsive element associated with saidresistance heating element and operated thereby to establish amoinentary short circuit therearound.

2. A starting circuit for a gaseous discharge lamp and the likecomprising heating filament discharge electrodes connected on one siderespectively with supply line conductors, a resistance heating elementconnected with the other sides of the electrodes so as to be in seriestherewith across the line and having a currentvoltage characteristiccharacterized by a rapid and out-of-proportion increase in amperage flowupon increase in voltage above the operating voltage of the lamp, and athermally responsive element associated with said heat resistant elementand adapted to momentarily short-circuit the same in response to theheat dissipation arising from the large flow of current through theresistance element at starting.

3. A starting mechanism for gaseous discharge lamps and the likecomprising a resistance heater element connected in multiple with thelamp and having a current-voltage characteristic characterized by arapid and out-oi-proportion increase in current flow at voltages abovethe operating voltage of the lamp, and a thermally responsive elementassociated with said heater element and operative to momentarilyshort-circuit the same upon a predetermined current flow therethro lgh.

4. The combination of a gaseous discharge device with a starting andoperating circuit therefor comprising an envelope with heatingelectrodes therein, a resistance heating element connected in serieswith said electrodes and having a voltagecurrent characteristiccharacterized by the rapid and out-of-proportion increase in amperagewith increase in voltage above the range of the operating voltage of thedevice, and a thermally responsive element associated with saidresistance heating element and operated thereby to establish a momentaryshort circuit there-around, the resistance heater element containingsilicon carbide as the predominating constituent.

5. A starting circuit for a gaseous discharge lamp and the likecomprising heating filament discharge electrodes connected on one siderespectively with supply line conductors, a resistance heating elementconnected with the other sides of the electrodes so as to be in seriestherement at starting, the resistance element containing silicon carbideas the predominating constituent.

6. A starting mechanism for gaseous discharge lamps and the likecomprising a resistance heater element connected in multiple with thelamp and having a current voltage characteristic characterized by arapid and out-oI-proportion increase in current flow at voltages abovethe operating voltage of the lamp, and a thermally responsive elementassociated with said heater element and operative to momentarilyshort-circuit the same upon a predetermined current flow therethrough,the resistance element containing silicon carbide as the predominatingconstituent.

'7. A starting mechanism for gaseous discharge lamps and the likecomprising a resistance heater element connected in multiple with thelamp and having a current voltage characteristic characterized by arapid and out-oi-proportion increase in current flow at voltages abovethe operating voltage of the lamp, and a thermally responsive elementassociated with said heater element and operative to momentarilyshort-circuit the same upon a predetermined current flow therethrough,the resistance heater element being of Thyrite.

8. A starting mechanism for gaseous discharge lamps and the likecomprising a resistance heater element connected in multiple with thelamp having a current voltage characteristiccharacterized by a rapid andout-oi-proportion increase in current flow at voltages above theoperating voltage of the lamp, and a thermall; r sponsive elementassociated with said heater element and operative to momentarilyshort-circuit the same upona predetermined current flow therethrough,the resistance heater element being formed of carborundum.

9. A starting mechanism for gaseous discharge lamps and the likecomprising a resistance heater element connected in multiple with thelamp and having a current voltage characteristic characterized by arapid and out-oiproportion increase in current flow at voltages abovethe operating voltage of the lamp, and a thermally responsive elementassociated with said heater element and operative to momentarilyshort-circuit the same upon a predetermined current flow therethrough,the resistance heater element containing silicon carbide and otherconstituents, the silicon carbide being the predominating constituent.

10. A starting mechanism for gaseous discharge lamps and the likecomprising a resistance heater element connected in multiple with thelamp and having a current voltage characteristic characterized by arapid and out-of-proportion increase in current flow at voltages abovethe operating voltage of the lamp, and a thermally responsive elementassociated with said heater element and operative to momentarily short-circuit the same upon a predetermined current flow therethrough, theresistance heater clement containing silicon carbide and carbon, thesilicon carbide being the predominating constituent.

11. A control circuit comprising a resistance element having avoltage-current characteristic characterized by a gradual increasein'amperage up to from So to ice volts and by more rapid andout-oi-proportion rise in current at higher voltages, and a controlelement responsive to the rapid and out-of-proportion increase inamperage for momentarily establishing a short circuit around theresistance element.

12. A control circuit comprising a resistance element having a voltage-cim'ent characteristic characterized by a gradual increase in amperageup to from so to we volts and by a more rapid and out-of-proporticn risein current at higher voltages, and a control element responsive to therapid and out-of-proportion increase in amperage for momentarilyestablishhig a short circuit around the resistance element, theresistance heater element being composed of carborundum. 13. A controlcircuit comprising a resistance element having a current-voltagecharacteristic characterized by a rapid and out of-proportion rise incurrent flow at predetermined voltages, a control element responsive tothe rapid and out of-proportion increase in amperage i'or momentarilyestablishing a short circuit around the resistance element.

14. A control circuit comprising a resistance heater element having acurrent-voltage characteristic characterized by a rapid and outof-proportion rise of current at predetermined voltages, and a thermallycontrolled element operated by the heat dissipated from said heatresistor for momentarily short-circuiting the resistance element.

15. A starting mechanism for fluorescent lamps comprising a resistanceheater element having a current-voltage characteristic characterized bya gradual increase in amperage up to from 80 to 100 volts and by a morerapid and out-of-proportion increase in currentfiow at higher voltagesand a thermally responsive element associated Withthe heater element andoperated to momentarily short-circuit the same upon a predeterminedcurrent flow therethrough.

16. A starting circuit for a gaseous discharge lamp and the likecomprising heating filament discharge electrodes connected on one siderespectively with supply line conductors, a resistance heating elementconnected with the other sides of the electrodes so as to be in seriestherewith across the line and having a current-voltage characteristiccharacterized by a rapid and out of-proportion increase in amperage flowupon increase in voltage above the operating voltage of the lamp, areactance in series with the discharge lamp, and a thermally responsiveelement associated with said heat resistant element and adapted tomomentarily short-circuit the same in response to the heat dissipationarising from the large how of current through the resistance element atstarting.

17. A starting mechanism for gaseous discharge lamps and the like havingheater filament discharge electrodes therein, comprising a resistanceheating element connected in series at starting with said electrodes andhaving a current voltagev characteristic characterized by a rapid andoutofiproportion increase in amperage flow upon increase in voltage, areactance in series with the discharge lamp and a thermally responsiveele ment associated with said heat resistance element and adapted tomomentarily short-circuit the same in response to the heat dissipationarising from the large flow of current through the resistance element atstarting whereby upon the initial closure of the circuit sumclentcurrent flows through the resistance heating element to operate thethermally responsive element to cause the me to momentarilyshort-circuit the heater elet with increased heating of the dischargeodes upon such short-circuiting operation a with the prompt opening ofthe short-circuit upon the re-cooling oi the heat resistance heatingelement and the application of the starting voltage to the lamp.

18. A circuit for a gaseous discharge lamp and the like comprisingheating filament discharge electrodes connected on one side respectivelywith supply line conductors, a resistance element connected with theother sides of the electrodes so as to be in series therewith across theline, said resistance element having a current voltage characteristiccharacterized by a gradual increase in current flow up to from to voltsand a rapid and out-of-proportion increase in amperage flow uponincrease in voltage above 100 volts, a reactance in series with thedischarge lamp, and a control element responsive to the rapid andout-of-proportion increase in amperage for momentarily short-circuitingsaid resistance element at starting.

19. The combination of a gaseous discharge device with a starting andoperating circuit there for comprising an envelope with heatingelectrodes therein,'a resistance element connected in series with saidelectrodes and having a voltagecurrent characteristic characterized by agradual increase in amperage up to from 80 to 100 volts and by a rapidand out-of-proportion increase in amperage at voltages above 100 voltsand a control element responsive to the rapid and out-0fproportionincrease in amperage for momentarily establishing a short-circuit aroundthe resistance element.

20. The combination of a gaseous discharge device with a starting andoperating circuit therefor comprising an envelope with heatingelectrodes therein, a resistance element connected in series with saidelectrodes and having a voltagecurrent characteristic characterized by agradual increase in amperage up to from 80 to 100 volts and by a morerapid and out-of-proportion increase in amperage at voltages above 100volts and a thermally responsive element responsive to heat generated bythe rapid and out-oi-proportion increase in current for momentarilyestablishing a short-circuit around the resistance element.

SITZER.

